package leetcode.acm;

import java.util.Scanner;

/**
 * @author mazouri
 * @create 2021-09-26 21:56
 */
public class _3400 {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder();
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        char A = 'A';
        sb.append("A");
        for (int i = 1; i < n; i++) {
            String prev = sb.toString();
            sb.append((char) (A+i)).append(prev);
        }
        System.out.println(sb.toString());
    }
}
